AddISToCourse needs Diff view, not just current.

application/modules/courses/controllers/ViewController.php

@@ -23,7 +23,7 @@ class Courses_ViewController extends App_Controller_Action
             $course = Courses_CourseModel::findLatestOfRequest($request);
 
 	        $parentCourse = null;
-	        if (in_array($request->getType(), array('ChangeCourse', 'AddACEAndChangeCourse'))) {
+	        if (in_array($request->getType(), array('ChangeCourse', 'AddISToCourse', 'AddACEAndChangeCourse'))) {
 	            $parentCourse = Courses_CourseModel::findParentOfRequest($request);
 	        }
 	        $initialRequest = false;